OPERATORS in C Programming Dr. P. Lawrence Rozario Raj Assistant Professor, Department of Mathematics, St. Joseph’s College Trichirappalli – 620 002, Tamil Nadu, India. lawraj2006@yahoo.co.in

OPERATORS in C Programming C supports a rich set of operators OPERATORS in C Programming C supports a rich set of operators. An operator is a symbol that tells the computer to perform certain mathematical or logical manipulations. Operators are used in programs to manipulate data and variables.

C operators can be classical into. 1. Arithmetic operators. 2 C operators can be classical into 1. Arithmetic operators. 2. Relational operators. 3. Logical operators. 4. Assignment operators. 5. Increment operators. 6. Conditional operators. 7. Bitwise operators. 8. Special operators.

1. ARITHMETIC OPERATORS C provides all the basic arithmetic operators 1. ARITHMETIC OPERATORS C provides all the basic arithmetic operators. Operator Meaning   + Addition or unary plus - Subtraction or unary minus * Multiplication / Division % Modulo division  

Integer division truncates any fractional part Integer division truncates any fractional part. The modulo division produces the remainder of an integer division. Integer Arithmetic When both the operands in a single arithmetic expression such as a+b are integers, the expression is called an integer expression, and the operation is called integer arithmetic. Integer arithmetic always yield an integer value. Examples of arithmetic operators are: a– b a + b a * b a / b a % b -a * b Here a and b are variables and are known as operands. The modulo division operator % cannot be used on floating point data.   a = 14 and b = 4 then a – b = 10 , a + b = 18, a * b = 56, a / b = 3 (decimal part truncated) , a % b = 2 (remainder of division)

Real Arithmetic An arithmetic operation involving only real operands is called real arithmetic. A real operand may assume values either in decimal or exponential notation. Since floating point values are rounded to the number of significant digits permissible, the final value is an approximation of the correct result. If x, y, and z are floats, then we will have; x = 6.0/7.0 = 0.857143 y = 1.0/3.0 = 0.333333 z = -2.0/3.0 = - 0.666667 the operator % cannot be used with real operands. Mixed-mode Arithmetic When one of the operands is real and the other is integer, the expression is called a mixed-mode arithmetic expression. If either operand is of the real type, then only the real operation is performed and the result is always a real number. Thus 15/10.0 = 1.5 Where as 15/10 = 1  

2. RELATIONAL OPERATORS Comparisons can be done with the help of relational operators. Relational Operators Operator Meaning < is less than <= is less than or equal to > is greater than >= is greaten than or equal to = = is equal to ! = is not equal to  

A simple relational expression contains only one relational operator and takes the following from: ae–1 relational operator ae-2     ae-1 relational operator ae-2 ae-1 and ae-2 are arithmetic expressions. Which may be simple constants, variables or combination of them. Examples of simple relational expressions and their values: 4.5 <= 10 TRUE 4.5 < -10 FALSE When arithmetic expressions are used on either side of a relational operator, the arithmetic expressions will be evaluated first and then the results compared. That is, arithmetic operators have a higher priority over relational operators. Relational expressions are used in decision statements such as, if and while to etc.

3. LOGICAL OPERATORS C has the following three logical operators 3. LOGICAL OPERATORS C has the following three logical operators. & & meaning logical AND || meaning logical OR ! meaning logical NOT The logical operators && and are used when we want to test more than one condition and make decisions. Example : a > b && x = = 10 An expression of this kind which combines two or more relational expressions is termed as a logical expression or a compound relational expression.

The logical expression given above is true only if a>b is true and x = = 10 is true. If either (or both) of them are false, the expression is false. Truth Table   op-1 op-2   Non-zero Non-zero 1 1 Non-zero 0 0 1 0 Non-zero 0 1 0 0 0 0   Example: if (age > 55 && salary < 1000) if (number < 0 number > 100)

4. ASSIGNMENT OPERATORS Assignment operators are used to assign the result of an expression to a variable. We have seen the usual assignment operator, ‘ = ’. In addition, C has a set of ‘shorthand’ assignment operators of the form v op = exp    Where v is a variable, exp is an expression and op is a C binary arithmetic operator. The operator op = is known as the shorthand assignment operator. The assignment statement v op = exp; is equivalent to v = v op (exp); with v evaluated only once. Consider an example x + = y + 1 This is same as the statement x = x + (y + 1); The shorthand operator + = means ‘add y+1 to x’ or ‘increment x by y+1’. For y = 2, the above statement becomes x + = 3; and when this statement is executed, 3 is added to x. If the old value of x is, say 5, then the new value of x is 8.

Shorthand Assignment Operators. Statement with simple. Statement with Shorthand Assignment Operators Statement with simple Statement with Assignment operator shorthand operator   a = a + 1 a + = 1 a = a – 1 a - = 1 a = a * (n +1) a * = n+1 a = a / (n +1) a / = n + 1 a = a % b a % = b   The use of shorthand assignment operators has three advantages: 1 What appears on the left-hand side need not be repeated and therefore it becomes easier to write. 2. The statement is more concise and easier to read. 3 The statement is more efficient.

5. INCREMENT AND DECREMENT OPERATORS C has two very useful operators not generally found in other language. These are the increment and decrement operators: + + and - - The operator + + adds 1 to the operand while - - subtracts 1. Both are unary operators and take the following form: + +m; or m + +; - - m; or m - -; + +m; is equivalent to m = m + 1; (or m + = 1;) - - m; is equivalent to m = m – 1; (or m - = 1;) We use the increment and decrement statements in for and while loops extensively. While + + m and m + + mean the same thing when they from statements independently, they behave differently when they are used in expressions on the right-hand side of an assignment statement.

Consider the following:. m = 5; Consider the following: m = 5; y = + +m; In this case, the value of y and m would be 6. Suppose, if we rewrite the above statements as m = 5; y = m ++; then, the value of y would be 5 and m would be 6.   A prefix operator first adds 1 to the operand and then the result is assigned to the variable on left. On the other hand, a postfix operator first assigns the value to the variable on left and then increments the operand.

6. CONDITIONAL OPERATOR A ternary operator pair “ 6. CONDITIONAL OPERATOR A ternary operator pair “?:” is available in C to construct conditional expressions of the form exp1? exp2 : exp3;   where exp1, exp2, and exp3 are expressions: The operator ? : works as follows : exp1 is evaluated first. If it is nonzero (true), then the expression exp2 is evaluated and becomes the value of the expression. If exp1 is false, exp3 is evaluated and its value becomes the value of the expression. Note that only one of the expressions (either exp2 or exp3) is evaluated. Example : a = 10; b = 15; x = (a>b) ? a : b; then x = 15.

7 . BITWISE OPERATORS C has a distinction of supporting special operators known as bitwise operators for manipulation of data at bit level. These operators are used for testing the bits, or shifting them right or left. Bitwise operators may not be applied to float or double.   Bitwise Operators   Operator Meaning & bitwise AND | bitwise OR ^ Bitwise exclusive OR << shift left >> shift right ~ One’s complement  

8 . SPECIAL OPERATORS C supports some special operators of interest such as comma operator, sizeof operator, pointer operators (& and *) and member selection operators (.and ->) and preprocessor operators (# and ##). The Comma Operator The comma operator can be used to link the related expressions together. A comma-linked list of expressions are evaluated left to right and the value of right-most expression is the value of the combined expression. Example: value = (x = 10, y = 5, x+y); For (n=1, m = 10; n<=m; n ++, m ++)

The sizeof Operator The sizeof is a compile time operator and, when used eith an operand, it returns the number of bytes the operand occupies. The operand may be a variable, a constant or a data type qualifier. Examples: m = sizeof(sum); n = sizeof(long int); k = sizeof(235L); The sizeof operator is normally used to determine the lengths of arrays and structures when their sizes are not known to the programmer. It is also used to allocate memory space dynamically to variables during execution of a program.